1. Field of the Invention
The present invention relates to a display character observation apparatus suitable for a still camera, a video camera, or the like and, more particularly, to a display character observation apparatus which displays a display character of a distance measurement range, a photometric range, or the like at an arbitrary position in a photographing frame, so that an object image formed by a photographing lens and the display character can be simultaneously observed through a finder system.
2. Related Background Art
In a conventional single-lens reflex camera, or the like, an object image formed on a focusing screen formed by a photographing lens and a display character of a distance measurement range, a photometric range, or the like located on the focusing screen or at a position optically equivalent to that of the focusing screen are simultaneously observed through a finder system. As an example of displaying a distance measurement range, a proposal in which a liquid crystal display is arranged on a predetermined imaging plane in a camera body of a single-lens reflex camera is known (Japanese Patent Laid-Open No. 62-47612). However, this proposal results in a dark screen, and an increase in cost. Japanese Patent Laid-Open No. 53-32048 describes an arrangement wherein a holographic mark is formed on a flat plate arranged near a predetermined imaging plane in a camera body, and is illuminated with light propagating through the flat plate. In this case, the thickness of the flat plate tends to be increased.
In a finder system of a single-lens reflex camera, a condenser lens or a fresnel lens is arranged before or after a focusing screen, so that a light beam from an object image on the focusing screen is efficiently incident on an eyepiece of the finder system.
In general, the thickness of a fresnel lens can be decreased as compared to that of a condenser lens, and a finder system can be easily made compact.
For this reason, fresnel lenses are used in many finder systems. Therefore, a fresnel lens must be arranged so as not to interfere with a display.
Note that such an arrangement is disclosed in Japanese Patent Laid-Open No. 1-277225.